Fabrication of jelly-roll Nb3Al superconductors by using Al-alloy sheets

Recently it has been reported that the critical current density of rapid-heating, quenching, and transformation (RHQT) Nb₃Al superconductor for high fields was vastly improved by Cu additions. That superconductor was made by rod-in-tube (RIT) process. In this work we tried to fabricate a Cu added Nb₃Al superconductor by jelly-roll (JR) process, which is one of practical processes of Nb₃Al superconductor fabrication. We fabricated a miniature sized billet and completed the drawing of multifilamentary wire of 1.10 mm in diameter and 41 m in length with no breakage. A sample subjected to the RHQT showed a core J_c (4.2 K) of 62 A/mm² at 24 T and exceeded the ordinary RHQT Nb₃Al JR superconductor (without Cu addition) in core J_c at high fields.